1. Technical Field
The present disclosure relates to a backlight device including a plurality of light sources and a liquid crystal display apparatus equipped with the backlight device.
2. Description of the Related Art
The liquid crystal display apparatus has features such as thin-screen, low power consumption, and high definition, and is prevailing in the field of television receivers along with increase in the screen size due to development of manufacturing technology. However, it has been pointed out that the liquid crystal display has a low contrast (dynamic range) of displayed images due to a display method. For this reason, in recent years, technology related to improvement in the quality of displayed images is further along in development.
A liquid crystal display apparatus used for television receivers is equipped with a backlight device that illuminates the entire display surface from the rear side. A plurality of granular light-emitting diodes (light-emitting diode, hereinafter denoted by an LED) arranged on the back side of a liquid crystal panel are used as light sources of the backlight device. In order to obtain a uniform luminance over the entire region illuminated by the plurality of light sources, a light reflection sheet is provided on the side opposite to the side in which the liquid crystal panel is installed, or a light diffusion plate is provided between the liquid crystal panel and the light sources. Also, as is disclosed in Japanese Unexamined Patent Application Publication No. 2011-151002, the reflection sheet is divided into a plurality of reflection regions by providing a lattice-shaped partition on the reflection sheet, the reflection regions are provided with the above-mentioned respective light sources, and luminance control reflection region by reflection region (also called area control or local dimming) is made possible while the interference from the light sources between the reflection regions is being reduced by the partition (see PTL 1). Consequently, for instance, when a scene, which is divided into a bright portion and a dark portion in the screen, is displayed, the luminance is controlled on a per reflection region basis according to the brightness of each portion so that the contrast between the portions is increased.
In a conventional liquid crystal display apparatus, mitigation of the effect by the partition on the uniformity of luminance in each of the reflection regions is insufficient, and thus undesirable variation in the luminance occurs in each of the reflection regions. As a result, a problem arises in that the contrast between a bright portion and a dark portion in the screen cannot be sufficiently increased in the entire backlight device.